title: β-Thujaplicinol inhibits hepatitis B virus replication by blocking the viral ribonuclease H activity.
abstract: Hepatitis B virus (HBV) is a hepatotropic DNA virus that replicates by reverse transcription. It chronically infects >350 million people and kills about 1 million patients annually. Therapy primarily employs nucleos(t)ide analogs that suppress viral DNA synthesis by the viral reverse transcriptase very well but that rarely cure the infection, so additional therapies are needed. Reverse transcription requires the viral ribonuclease H (RNAseH) to destroy the viral RNA after it has been copied into DNA. We recently produced active recombinant HBV RNAseH and demonstrated that Human Immunodeficiency Virus (HIV) RNAseH antagonists could inhibit the HBV enzyme at a high frequency. Here, we extended these results to β-thujaplicinol, a hydroxylated tropolone which inhibits the HIV RNAseH. β-Thujaplicinol inhibited RNAseHs from HBV genotype D and H in biochemical assays with IC₅₀ values of 5.9±0.7 and 2.3±1.7 μM, respectively. It blocked replication of HBV genotypes A and D in culture by inhibiting the RNAseH activity with an estimated EC₅₀ of ∼5 μM and a CC₅₀ of 10.1±1. 7 μM. Activity of β-thujaplicinol against RNAseH sequences from multiple HBV genotypes implies that if chemical derivatives of β-thujaplicinol with improved efficacy and reduced toxicity can be identified, they would have promise as anti-HBV agents.
authors.affiliation: Key Laboratory of Molecular Biology on Infectious Diseases, Ministry of Education, Second Affiliated Hospital, Chongqing Medical University, 1 Yi Xue Yuan Road, Yuzhong District, Chongqing 400016, People's Republic of China; Department of Molecular Microbiology and Immunology, Saint Louis University School of Medicine, 1100 S. Grand Blvd., Saint Louis, MO 63122, USA. Electronic address: biotottyhy@yahoo.com.cn.
authors.forename: Yuan
authors.initials: Y
authors.lastname: Hu
authors.forename: Xiaohong
authors.initials: X
authors.lastname: Cheng
authors.forename: Feng
authors.initials: F
authors.lastname: Cao
authors.forename: Ailong
authors.initials: A
authors.lastname: Huang
authors.forename: John E
authors.initials: JE
authors.lastname: Tavis
mesh_terms: D000998:Antiviral Agents / Q000494:pharmacology*; D045744:Cell Line, Tumor; D006509:Hepatitis B / Q000188:drug therapy* / Q000821:virology; D006515:Hepatitis B virus / Q000187:drug effects* / Q000201:enzymology / Q000235:genetics / Q000502:physiology; D006801:Humans; D016914:Ribonuclease H / Q000037:antagonists & inhibitors* / Q000235:genetics / Q000378:metabolism; D014334:Tropolone / Q000031:analogs & derivatives* / Q000494:pharmacology; D014764:Viral Proteins / Q000037:antagonists & inhibitors* / Q000235:genetics / Q000378:metabolism; D014779:Virus Replication / Q000187:drug effects*
chemical_list: D000998:Antiviral Agents; D014764:Viral Proteins; C497842:beta-thujaplicinol; D014334:Tropolone; D016914:Ribonuclease H
keywords: HBV; HBV core protein; HBV surface proteins; HBc; HBs; HIV; HRHPL; HRHPL-D702A; HepG2; Hepatitis B virus; Huh7; RC DNA; RNAseH; Reverse transcription; Ribonuclease H; a hepatoblastoma cell line; a human hepatoma cell line; active site mutant of recombinant HBV RNAseH; cccDNA; covalently-closed circular DNA; hepatitis B virus; human immunodeficiency virus; recombinant wild-type HBV RNAseH; relaxed circular DNA; ribonuclease H; β-Thujaplicinol; β-thujaplicinol; βTJ